Studies of the protonation equilibria of sulphamates using ¹³C and ¹C nuclear magnetic resonance spectroscopic, potentiometric, and conductimetric methods

pK_a Values are determined for the ionization RNH₂SO₃⇌RNHSO₃- + H⁺ for sulphamates with R = Buⁿ, PrⁿBu^a, and cyclohexyl using¹³C and ¹H n.m.r. spectroscopic, potentiometric. and conductimetric methods. These compounds have pK_a values in the range 1-1.9 and they are thus less acidic than sulphamic acid. Intramolecular standards were used in the n.m.r. measurements. The similarity in the pK_a values determined by the two n.m.r. methods suggests that solvation effects are small.